873912 - JS warning "anonymous function does not always return a value" resource:///modules/devtools/framework/target.js:218

Status: RESOLVED FIXED

(DevTools :: Debugger, defect, P3)

Description

[Daniel Holbert [:dholbert]]

I noticed this in the output of my debug build today (not sure exactly what triggered it, but that doesn't really matter because the warning is pretty clear on its own):
{
JS Component Loader: WARNING resource://gre/modules/commonjs/toolkit/loader.js -> resource:///modules/devtools/framework/target.js:218
                     anonymous function does not always return a value
}

The code in question is:
> 218   get window() {
> 219     // Be extra careful here, since this may be called by HS_getHudByWindow
> 220     // during shutdown.
> 221     if (this._tab && this._tab.linkedBrowser) {
> 222       return this._tab.linkedBrowser.contentWindow;
> 223     }
> 224   },
https://mxr.mozilla.org/mozilla-central/source/browser/devtools/framework/target.js?rev=aeb0f8faf02b#218

...which, as the warning says, does not always return a value. (It's only got one return statement, which is inside of an "if".)

The function used to be an unconditional return (& hence not trigger this warning), but it was changed to its current form here:
 https://hg.mozilla.org/mozilla-central/rev/ca621a4ceaa1#l4.124
for bug 820524. (back when the file was named Target.jsm -- it's been renamed to target.js since then)

CC'ing :past and :jwalker (author and reviewer on that cset), in the hopes that at least one of you might know what the correct fix for this is. :)

Comment 1

[Daniel Holbert [:dholbert]]

(In reply to Daniel Holbert [:dholbert] from comment #0)
> CC'ing :past and :jwalker (author and reviewer on that cset), in the hopes
> that at least one of you might know what the correct fix for this is. :)

er, now CC'ing for real.

Comment 2

[Panos Astithas (he/him) [:past] (please ni?)]

Attachment: Patch v1

I hate these warnings.

Comment 3

[Panos Astithas (he/him) [:past] (please ni?)]

https://hg.mozilla.org/integration/fx-team/rev/69598cd0437c

Comment 4

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/69598cd0437c